When a well-meaning visitor from the future causes Barry to worry about the effects on the timeline, the team soon comes to discover that sending her back to her time isn't as easy as they originally thought.
As various members struggle with personal issues, they have their first encounter with Cicada, who is determined to wipe out all metahumans.
With the help of another version of Wells named Sherloque, the team tries to identify Cicada, but Sherloque soon comes to realize that Nora's presence has already altered the timeline. Cicada uses Joe to lure a member of the team into a confrontation.
Nora reveals why she has been giving Iris the cold shoulder. Blog articles about XS lead Team Flash to a shocking realization about the aftermath of an old foe's actions.
The emergence of a new meta leaves Barry's live hanging in the balance. Cisco decides that he needs to find a new way other than his powers to help Caitlin in her search for her father.
As Caitlin finds her father, Cisco grows suspicious of the story he told them. An attack leads to the reemergence of Killer Frost. Iris and Sherloque investigate a lead that could help the team identify Cicada.
Team Flash is drawn into a meta family feud when their newest villain, Weather Witch, turns out to be related to an old enemy. The history behind Cicada's vendetta against metahumans is revealed.
When the team's plan to stop Cicada drives Nora and Barry to time travel to get some necessary equipment, their trip causes them to face old enemies and reveals a shocking truth to Nora.
With the help of a book that can rewrite reality, a psyhiatrist causes Barry and Oliver to switch bodies, a fact that they have trouble getting their friends to believe. Out of options, they find their way to Earth-38 to enlist the help of Supergirl and Superman.
Nora is forced to step up to cover for Barry when an encounter with a new villain affects his phasing. As she tries to come to grips with the truth about Thawne's actions, Sherloque continues to covertly investigate her.
When a confrontation with Cicada leaves Nora in peril, Barry's mission to stop him takes a new turn that threatens to cause him to cross all boundaries. Cisco and Caitlin's meta cure hits a temporary hurdle that Killer Frost helps with.
Nora's desperation to protect her secret leads to a reckless act that leaves her trapped inside Grace's mind. As Barry and Iris try to save her, they uncover traumatic details from her past.
In need of a device to hold Cicada to administer the meta cure, Ralph and Barry go undercover to recover the device from a crime boss. Iris's life hangs in the balance when her investigation of a clue on Cicada leads to a confrontation with him.
With Barry inside the Speed Force, Nora is left to hold down the fort which she finds difficult when Cicada kidnaps Iris. As her attempts to resolve the situation keep backfiring, Nora is driven to the brink in her attempt to save those she loves.
With Gorilla Grodd plotting to control the minds of the Central City population, Team Flash finds an unlikely ally in King Shark, who risks his one chance of returning to normal to save the city.
As Thawne pushes Nora to resolve the situation with Cicada, Barry makes a plea to Cicada using the news about Grace being a meta.
As the timeline shifts, Thawne urges Nora to come clean to her parents. Sherloque discovers the truth about Nora's relationship with Thawne. Team Flash tries to save a meta from Cicada II.
The truth about Nora's real purpose unfolds, causing a rift between her and Barry. Team Flash learns the details of how Nora came to learn about her powers and be mentored by Thawne.
As Iris tries to reach Nora in the future, a furious Nora rebuffs her mother and takes drastic actions to time travel. Caitlin and Carla's lives hang in the balance when they are pursued by both Icicle and Cicada II.
Nora recruits a team of villains to aid her heist on McCulloch Technologies, but her plan backfires when they turn on her. Caitlin and Ralph discover that Cicada II has nefarious plans that involve the meta cure.
As Team Flash gears up for the final confrontation against Cicada II, Ralph comes to suspect that Thawne might have a hidden stake in the fight.
As Thawne's true plan comes to light, Team Flash is forced to make a hard decision. Nora realizes that the only way to stop Cicada II might put her time and her very existence in danger.